ABOUT BOWEL CANCER

Staging and grading

The stage and grade of a cancer can be two of the most important things to know when deciding how to treat bowel cancer.

What is staging?

Staging is the process of finding out how much cancer is in a person’s body and where it’s located. It’s how the doctor determines the stage of a person’s cancer.

Staging information is used to help plan treatment and predict a person’s prognosis. Bearing in mind we are all different, cancers with the same stage do tend to have similar outlooks and are often treated in the same way.

One of the tools specialists use to describe the stage is the TNM system. Using the results from your diagnostic tests and scans, specialists can use TNM to develop a shorthand description of your cancer.

In the TNM system, each cancer is assigned a letter or number to describe the tumor, node, and metastases.

  • T stands for the original (primary) tumour.
  • N stands for nodes. It tells whether the cancer has spread to the nearby lymph nodes.
  • M stands for metastasis. It tells whether the cancer has spread to other parts of the body.

The T category provides information about the original (primary) tumour, such as size, how deeply it has grown into the organ it started in, and whether it has grown into nearby tissues.

  • TX means the tumour can’t be measured.
  • T0 means there is no evidence of a primary tumour (it cannot be found).
  • Tis means that the cancer cells are only growing in the most superficial layer of tissue, without growing into deeper tissues. This may also be called in situ cancer or pre-cancer.
  • Numbers after the T (such as T1, T2, T3, and T4) might describe the tumour size and/or amount of spread into nearby structures. The higher the T number, the larger the tumour and/or the more it has grown into nearby tissues.

The N category describes whether the cancer has spread into nearby lymph nodes.

  • NX means the nearby lymph nodes cannot be evaluated.
  • N0 means nearby lymph nodes do not contain cancer.
  • Numbers after the N (such as N1, N2, and N3) might describe the size, location, and/or the number of nearby lymph nodes affected by cancer. The higher the N number, the greater the cancer spread to nearby lymph nodes.

The M category tells whether the cancer has spread (metastasised) to other parts of body).

  • M0 means that no distant cancer spread was found.
  • M1 means that the cancer has spread to other organs or tissues (distant metastases were found). 

Stage grouping

Once the values for T, N, and M have been determined, they are combined to assign an overall stage. There are five (5) stages: stage 0 (zero) and stages I through IV (1 through to 4).

Stage IV (4) is the highest and means the cancer is more advanced than in the lower stages. Sometimes stages are subdivided as well, using letters such as A and B.

Stage 0 is carcinoma in situ for most cancers. This means that abnormal cells have been found and these could develop into cancer and spread.

Stage I indicates the cancer is small and has not spread anywhere else.

Stage II indicates the cancer has grown but has not spread. Stage II is divided into Stage IIA, stage IIB and stage IIC depending on the size and spread of the cancer.

Stage III indicates the cancer is larger and may have spread to surrounding tissues and/or lymph nodes. Stage III is divided into stage IIIA, B and C depending on the size and spread of the cancer.

Stage IV indicates the cancer has spread from where it started to at least one other organ in the body. This is also known as ‘secondary’ or metastatic’ cancer.

Stage IV is divided into stage IVA, B and C depending on the size and spread of the cancer.

The stage of a cancer is determined at diagnosis and does not change over time, even if the cancer shrinks, grows, spreads, or recurs. The cancer is still referred to by the stage it was given when it was first diagnosed, although information about the current extent of the cancer is added. This is important to understand because survival statistics and information on treatment by stage for specific cancer types refer to the stage when the cancer was first diagnosed.

Grading

For most cancers, the grade is a measure of how abnormal the cancer cells look under the microscope. This is called differentiation. Grade can be important because cancers with more abnormal-looking cells tend to grow and spread faster. There are five grades starting with GX (where the tumour grade cannot be identified) through G1 to G4 (the highest grade).

In low-grade (well-differentiated) cancers, the cancer cells look a lot like cells from normal tissue. In general, these cancers tend to grow slowly. In high-grade (poorly differentiated) cancers, the cancer cells look very different from normal cells. High-grade cancers often tend to grow quickly and have a worse outlook, so they may need different treatments than low-grade cancers. Even when the grade doesn’t affect a cancer’s stage, it may still affect the outlook

Putting together your treatment plan
When all of the test results are known, your specialist can then discuss your prognosis what’s the difference between diagnosis and prognosis with his or her colleagues. This is known as a ‘multi-disciplinary team’ approach to cancer care where patient test results are reviewed by a number of specialists working together as a team. The meetings help specialists offer the best possible treatments to their patients and you may wish to ask if your plan has been, or will be, discussed at one of these meetings. All decisions will be made jointly between you and your medical team. It is very important to discuss with your doctors the advantages and disadvantages of proposed treatments so that your individual needs and wishes can be fully considered.